Usage

This module provides a layout which places all windows in a single
row; the size occupied by each individual window can be increased
and decreased, and a window can be set to use the whole available
space whenever it has focus.

You can use this module by including the following in your ~/.xmonad/xmonad.hs:

Haskell's Eq class is usually concerned with structural equality, whereas
what this layout really wants is for its elements to have a unique identity,
even across changes. There are cases (such as, importantly, Windows) where
the Eq instance for a type actually does that, but if you want to lay
out something more exotic than windows and your Eq means something else,
you can use the following.

ZoomRow layout with a custom equality predicate. It should
of course satisfy the laws for Eq, and you should also make
sure that the layout never has to handle two "equal" elements
at the same time (it won't do any huge damage, but might behave
a bit strangely).